Field of vision plotting device



Aug. 21, 1951 H. D. SHEKELS 2,564,794

FIELD OF VISION PLOTTING DEVICE Filed June 14, 1948 4 Sheets-Sheet 1 ATTGRNEYSE Aug. 21, 1951 H. D. SHEKELS 2,564,794

FIELD OF VISION PLOTTING DEVICE Filed June 14, 1948 4 Sheets-Sheet 2 FIELD PLOT NAME DATE

INVENTOR.

HOWARD D.5HEREL$;

ATTORNEYS Aug. 21, 1951 H. D. SHEKELS FIELD OF VISION PLOTTING DEVICE Filed June 14, 1948 4 Sheets-Sheet 5 FIG. 10

gwue/wtm HOWARD D. SHEKELS Aug. 21, 1951 Filed June 14, 1948 H. D. SHEKELS FIELD OF VISION PLOTTING DEVICE 4 Sheets-Sheet 4 Fl 0. a 9

JNVENTOR. HOWARD D. SHEKELS ATTORNEYS Patented Aug. 21, 1951 UNITED STATES PATENT OFFICE FIELD F VISION PLOTTIN G DEVICE Howard D. Shekels, St. Paul, Minn.

Application June 14, 1948, Serial N 0. 32,765

Claims.

This invention relates to methods and apparatus for determining and plotting the field of vision of the human eye.

It is now recognized by oculists that, if the field of vision of a human eye can be plotted, the plot will be highly useful to the o'culist in analyzing deficiencies of sight as well as improper functi'o'iiing of other parts of the human system. If plots of the field of vision of the eye are once or successively taken and abnormal conditions are found in the field of vision, steps can often be taken in the way of remedial medical treatment to discover and sometimes overcome or check conditions that may be detrimental to the health of the patient. Thus, for example, in certain instances it is possible to discover brain tumor through plotting field of vision of the eyes prior to the time that the brain tumor manifests itself in other ways, and by remedial operation it is possible to remove the tumor prior to the time that a malignant growth, such as a cancer, has developed. In other instances it is possible to spot conditions causing pressure on certain nerves and to thereafter remedy these conditions. It is highly important, therefore, to the medical profession that there be available a simple and fast method and apparatus for determining and plotting the field of vision of the human eye, and it is one of the objects of this invention to provide such a method and apparatus.

More Specifically, it is an object of the present invention to provide a method of plotting the field of vision of the human eye which consists generally in intermittently exposing a light at numerous spaced points in a predetermined path located in a plane substantially normal to the straight forward line of vision of the eye and recording on a chart, representing the possible field of vision of the eye, the relative positions that the light source is seen as it is exposed at the predetermined points, whereby a graph of the field of vision of the eye is secured.

Another object is to provide a simple apparatus which can be readily employed in a doctors oilice to quickly secure a graph of the field of vision of the human eye.

A more detailed object is to provide a screen on which a beam of light may be thrown intermittently in a predetermined path at numerous spaced points radially and circumferentially spaced from a central point on the screen toward which the eye of the patient is directed and to provide a chart representing the possible field of vision of the eye along with a recording'mecha nism under the control of the patient which can be actuated each time that the beam of light is seen to secure an impression on the chart which will correspond in its representation on the chart to the position that the light beam will appear on the screen when it is seen by the eye.

The objects advantages of the invention will more fully appear from the following description made in connection with the accompanying drawings, wherein there is shown an apparatus for carrying out the methods of the invention and in which:

Fig. 1 is a view in side elevation of the apparatus in closed up condition;

2 is a perspective view of the apparatus with the front and top cases removed and with the head locating device extended;

Fig. 3 is a vertical section through the device, showing it in enlar ed scale and showing the device in use;

Fig. 4 is a vertical section taken substantially on the line i i of Fig. 3 as is indicated by the arrows;

Fig. 5 is a vertical section taken substantially on the line 5 of Fig. 3 as is indicated by the arrows;

Fig. 5 is a view on a still larger scale illustrating the light carriage and associated parts, cer-' tain of the parts being broken away and shown in section;

Fig. 7 is a horizontal section taken on the line 7-4 of Fig. 6 as indicated by the arrows;

Fig. 8 is a view in enlarged scale of the recording head, the View being taken substantially on the line 88 of Fig. 9 and showing the parts in longitudinal section;

Fig. 9 is a transverse section taken substantially on the line 9-9 of Fig. 8;

Fig. 1G is a sectional detail illustrating the sliprin construction for carrying an electrical current to the light carriage;

Fig. 11 is a plan view of a chart employed with the machine for plotting the field of vision of the human eye;

Fig. 12 is a wiring diagram of the device; and

Figs. 13, 14, and 15 are diagrammatic views illustrating the operation of the recording head.

The apparatus will be first described, whereupon the general operation of the device will be described.

The apparatus includes a main box-like casing is equipped with a removable front section I! and a removable top rear section I8, the main casing being equipped with suitable handles for carrying it and the main casing and front section l1 and top rear section I8 being also equipped with cooperating fastening elements for removably securing the three parts together. The front section fits over a rectangular frame H), which is fitted into the front side of the main casing Hi. This frame in turn carries what may be termed generally as a screen A. Mounted in the lower part of the frame I!) is a bail-like extensible bracket 20, which carries at its forward end a clamping socket 2| within which an angular standard 22 may be secured. Mounted on the forward portion of the standard 22 is a chin rest 23 for receiving the chin of the patient in such relation that either eye of the patient may be located directly forward of the center of the screen A. The chin rest 23 is swiveled on the standard 22, and the central portion of the chin rest is offset from the standard 22, whereby when the chin rest is located as shown, the head will be located centrally somewhat to the right of the center of the screen A, while as the chin rest 23 is turned through 180, the chin rest will be centered to the left of the standard 22. Normally the device will be supported as upon a suitable stand or table 24, and in order to better brace the head of the patient a small pivoted bail-like support 25 is attached to the clamping socket 2| which can be swung down to rest on the table. By loosening the thumb screw of the clamping socket 2|, the standard 22 can be raised or lowered so as to permit of vertical adjustment for locating the eyes of different individuals at the proper level relative to the center of the screen A.

A horizontal shaft 26 is journaled in suitable bearings 21 dependin from the upper portion of the casing l6 behind the screen A. This shaft carries at its forward end a U-shaped frame 28, which will revolve with the shaft, and extending between the two arms of this frame adjacent the forward ends thereof are a pair of guide rods 29 on which a carriage 30 is slideably mounted. The carriage 30 forms an enclosed light housing 3|, and in this housing is located an electric light socket 32, in which a light bulb 33 is mounted. Aligned with the central portion of the light bulb 33 is a forwardly projecting light tube 34 through which a beam of light from the bulb 33 may shine. Also attached to the housin 3| is a bracket 35 carrying a forwardly projecting pin 36 on which a roller 3? is journaled. A counterbalancing weight 38 is secured to an arm 39 projecting from the lower portion of the frame 28 to counterbalance the effect of the opposite portion of the frame from that portion to which the arm 39 is secured, the frame extending generally in a direction away from the shaft 26 opposite the counterbalancing weight 38.

While the screen A can be variously formed, in the illustrated embodiment it includes a backme plate 40 havin secured to its rear side a spiral track 4|, within adjacent convolutions of which both the light tube 34 and the roller 31 are received. Accordingly, as the shaft 26 is revolved, the light carriage 3|), sliding on the guide rods 29, will be controlled in its radial movement to and from the axis of the shaft 26 by the spiral track 4 I. The backin plate 40, at preferably regularly spaced intervals between adjacent sections of the track 4|, 42 into alignment with which the light tube 34 is adapted to be successively brought during the rotation of the shaft 26. The backing plate 40 carries studs 43, which may be equipped with wing nuts 44. Replaceably mounted on the studs 43 in front of the backing plate 40 is a colored filter is equipped with light apertures plate 45, and forward of the filter plate 45 and also removably mounted on the studs 43 is a solid plate 46 having small openings 41 aligned with the openings 42 in the backing plate 40 but preferably of somewhat smaller diameter than the opening 42; Forward of the plate 46 and also removably mounted on the stud 43 is a diffusion plate 43, which will preferably be made of translucent or transparent plastic having its rear surface ground or roughened so as to tend to cause diifusion of a light beam projected from the bulb 33 through the light tube 34, apertures 42, colored filter plate 45, and apertures 41 in the plate 43. Centrally located at the forward side of the diffusion plate 48 in alignment with the shaft 26 is a target 43, which will be employed as a focal point for the eye of the patient and which will be colored or printed in contrast to the remainder of the plate 48, or may be a mirror.

Mounted on suitable bearings 50 attached to the casing I6 is a vertical turntable shaft 5| having a head at its upper end to which is attached a backing plate 52 and a turntable 53, which overlies the backing plate 52. On the surface of the turntable are suitable securing devices, such as the corner receivers 54, for holding in place a chart on the surface of the turntable, such as the chart B, which will be more fully described in detail hereafter. Attached to the backing plate 52 is a spiral trackway 55, which projects downwardly therefrom and which trackway is generally similar to the trackway 4| previously described but which may be of smaller proportionate dimension. An upstanding guide bracket 55 is mounted on the rear upper portion of the easing l6, and slideably received through an opening, such as a square opening, in this bracket is a shank 51 of square shape to which is secured an upper arm 58, which overlies the turntable 53, and a lower arm 59, which underlies the spiral track 55. The lower arm 59 carries at its forward portion a pair of vertical roller pins 50, which may be received within adjacent channels of the spiral track 55. Mounted on the upper arm 58 to overlie the turntable 53 and the chart B that will normally be mounted thereon is a recording head designated as an entirety by the letter C. With the arrangement described, it will be seen that the recording head C will normally project over the chart B on the turntable 53 and that it will be moved inwardly and outwardly along a line radial to the axis of rotation of the turntable shaft 5| by being guided in the guide bracket 56 by the rollers 60 received in the spiral guideway 45.

While it is possible to drive the two shafts 26 and 5| in any suitable manner, in the illustrated embodiment there is provided for the purpose a reversible electric motor 3| mounted within the casing [6, this motor including a motor shaft 62 on which a friction wheel 53 is secured. As best seen in Fig. 5, the friction wheel 63 engages a larger friction wheel 64 mounted on a cross shaft 65, journaled in a suitable bearing 65, supported from the casing H5. The shaft 65 in turn carries a worm 61 intermeshing with a worm gear 68 mounted on a vertical countershaft 39 journaled in suitable bearings 15 carried by the casing It. The countershaft 69 carries a pinion H engaging with a larger gear 12 carried by the turntable shaft 5|. The turntable shaft 5| carries near its upper end a beveled pinion i3 engaging with a beveled gear 14 of similar size carried by the inner end of the shaft 25, which latter shaft may be designated the light shaft as distinguished from the turntable shaft. Any suitable speed reducinggearing may be substituted for that shown to drive the turntable shaft SI and the light shaft 26 at relatively slow speed, it being necessary, however, that both shafts turn at the same speed.

The turntable shaft 5! carries a screw running through a nut 78 attached to a microswitch actuating arm 1! guided in a slot formed in a bracket 78 mounted on a panel l9 suitably supported on a partition 88 mounted in the casing I6, the panel carrying two electric microswitches III and 82 respectively. The actuating buttons 81a and 82a of the two microswitches are disposed in opposing relation with a portion of the actuating arm 11 located between them. The two microswitches BI and 82 are employed, as will be presently brought out more clearly, to stop the motor- 6| as the shaft 5i is turned in either direction sufiiciently to carry the actuating arm 11 into engagement with one of the two buttons SIa or 820. of the two microswitches 8i and 82. Assuming that the motor Si is running in one direc tion, of course the shaft 5| will be turned in one direction, and as this occurs, the nut 16 will be vertically moved by the screw 15. Lets assume that the rotation of the turntable shaft 5! is such that the nut 15 will be drawn upwardly relative to the shaft 5I and that accordingly the actuating arm 17 will be drawn toward the button 8Ia of the microswitch 8I. When finally the actuating arm 1'! contacts the button 8 I a, the micro-. switch will be actuated, and actuation of this switch will break the motor circuit to the motor 5 I. Thereupon when the motor is again actuated. the circuit must be established through the other microswitch 82 and the motor will turn in the opposite direction than previously. Accordingly the nut IE will be lowered relative to the shaft El until the actuating arm 1'! engages the button 82a of microswitch 82, thereby opening the switch 82 and again breaking the circuit to the motor as the switch 82 is actuated. Of course as the actuating arm 11 moves away from either button am or 82a of either microswitch, that particular microswitch will again close.

The recording head C, as is best illustrated in Figs. 8 and 9, includes a panel 83, which is fixed to the forward end of the arm 58 which overlies the turntable 53. Pivot studs 84 are mounted in suitable brackets carried by this panel adjacent the two lower corners of the panel and adjacent the top left-hand corner as illustrated and journaled on these studs are spool-like rollers 85. A block 86 is mounted near the upper portion of the panel 83, and attached to this block is a spring arm 81 carrying a bracket 88, which projects over toward the right upper corner of the panel and carries at that point a pivot stud 89 on which a fourth spool-like roller 88 is journaled. A set screw BI is carried in the bracket 88 and it projects through the spring arm 8'! and it cooperates with the block 85 to limit the possible downward swinging movement of the roller 98, the set screw being adjustable in the bracket to vary this possible movement. Trained over the four rollers 85 and 98 is an endless ink-carrying typing ribbon 92, such as is commonly employed on typewriters. The lower run of this ribbon between the two lower rollers 85 extends close to the lower edge of the panel 83, and accordingly it is located close to the top of the turntable 53. Vertically mounted for sliding movement in a pair of lugs 93 attached to the panel 83 is a key 94, and the lower part of this key is preferably beveled, and the key- 6 is located so as to strike the lower run of the rib-' bon 92 between the two lower rollers 85. The key 94 is normally urged upwardly by a spring 95 attached to the lower lug 8,3 and of forked U formation, the forked portions of the spring strad-.

dling the key and engaging a short crosspin 96 carried by the pin. A block 91 is secured to the extreme right-hand corner portion of the panel 83, and this block carries a spring forked prong 88, which bears against the right side of the ribbon 82 as it works over the lower right-hand roller 85, and the two points of this prong, by preventing back travel of the ribbon 532, permit of movement of the ribbon over the four rollers and 98 only in a clockwise direction as, viewed in Fig. 8.

A relay 88 is also mounted on the panel 88, and this relay has a spring actuated armature I88, the upward movement of which is limited by an adjustable set screw Hill, and the outer end of the armature I88 overlies the upper end of the key 98. Obviously, as the relay 98 is energized, the armature I88 will be attracted and moved downwardly against the tension of the armature spring, thereby depressing the key 94 to move the key from the full-line position shown in Fig. 3 to the dotted line position there shown, and as this occurs, the lower run of the ribbon 92 will also be depressed. The movement of the key 98 will be sufficient for the key to press that portion of the ribbon 92 which it strikes against the chart B held on the turntable 53, as seen in Fig. 3, whereupon an impression will be printed by the ribbon on the said chart, this impression takin the form of a dot. As the lower run of the ribbon 82 is depressed by the key 88, the upper right-hand roller 88 will be depressed against the tension of the spring arm 81, the parts moving from about the position diagrammatically shown on Fig. 13

to the position shown in full lines in Fig. 14.

Thereupon as the relay 89 is deenergized, the armature spring 85 will raise the key 8 and as this occurs, some slack in the ribbon 82 will result, and the spring arm 81 will thereupon raise the roller 98 from the down position shown in Fig. 14 to the full-line position shown in Fig. l5. As this occurs, the prong 98 will prevent back travel of the ribbon 82 in a counterclockwise direction, and as a result the slack portion of the ribbon will cause a. slight advancement of the ribbon over the two left-hand rollers 85 and the roller 88. Zhen when the relay is again energized, the key 554 will strike a fresh portion of the ribbon instead of striking the same portion of the ribbon that it had previously engaged as the key is depressed.

Mounted on the lower side of the block 85 is a stud i232 carryin insulated washers I88, between which are located a pair of contacts I84 and I85 of an electrical switch, which may be designated as an entirety by the letter D. The contact i554 has a downwardly projecting arm with a reversely bent end which lies in the path of movement of the outer end of the armature 88 as the armature is attracted by the relay 99. The two contacts its and "i5 of the switch D are normally separated, but as the relay 89 is energized and the armature I88 is attracted, the contact I84 will be moved downwardly to establish engagement between the two contacts I84 and E85 of the switch D.

Attached by a spacer I88 to the rear of panel 83 is a plate Illl. An open-bottomed and open-backed housing I88 having suitable flanges at its top and side edges to receive the top and side edges of the plate It? may be removably enass Q94 7 gaged with the plate I'I to receive and enclose the major operating parts of the recording head C. The left side of this housing I03 is slotted to receive the overlyin arm 38 to which the panel 83 is secured.

There is supplied with the device a hand switch I09, which can be held in the hand of the patient whose field of vision is to be plotted, as is illustrated in Fig. 3, and this switch has a push key IIIQa, which can be pressed to close the switch and thereby energize the relay 99 of the recording head. Mounted on the upperpart of the casing I6 near the turntable 33 is a main line switch I I0 subject to hand actuation, while also mounted near the switch I I0 is a double pole, three position manual direction control switch, which is designated as an entirety by the letter E. Housed in the casing I6 but not otherwise illustrated except in the wiring diagram Fig. 12 are other electrical appliances.

Referring to Fig. and to Fig. 3, carried by the casing I3 adjacent the shaft 23 is a small block I I3a insulated from the casing by insulation I I31). Within a socket formed in the block II3a is located a carbon brush II3 urged by a spring H4 located within the socket into engagement with a slip-ring II5 mounted on the shaft 26 but insulated therefrom by the insulating collar IIB. Connected to the slip-ring H5 is a wire II'I carried by the frame 28, which connects with one terminal of the bulb socket 32, the other terminal of the bulb socket being ground to the frame A wire IIB running from a source of electricity is connected to the block I I3a.

Referring now to the wiring diagram illustrated in Fig. 12, there is there shown the main line switch IIO, the motor 0|, which is a reversible condenser type motor, a transformer IISI having primary and secondary windings, a rectifier I20, a relay actuated double-pole double-throw contact switch designated as an entirety by the letter- F, the recording head relay 09 with its armature I00, the switch D, the recording key 34, the light 33, the reversing switch E, and the two microswitches III and 32.

There is provided a power plug I2I, the two prongs of which are adapted to be plugged into a power circuit. From one contact of the power plug, a conductor I22 runs to one contact of the line switch I I0, while another conductor I II runs I.

from the other contact of the line switch to the primary winding of the transformer I I 3. Another conductor I I2 runs from the other end of the primary winding of the transformer back to the other contact of the power plug I2I, and accordingly a transformer circuit will be established when the line switch III? is closed from the plug I2I through the conductor I22, line switch III), conductor II I, to the primary winding of the transformer I I9, and thence through the conductor I I2 back to the power line through plug I2 I.

From the conductor II I another conductor I23 runs to one contact of the motor 6|. Another conductor I24 runs from another contact of the motor GI, to one of the two movable contacts I25 of the double-pole three-position switch E. The movable contact I25 is adapted to be selectively engaged with any one of three contacts I26, I21, and I28. From contact I23 a conductor I29 runs to the contact of microswitch BI. From the movable contact of the microswitch 8| a conductor I32 runs to a conductor I3I, which is connected to conductor II2 running to one contact of the power plug I2I. From contact I28 a conductor I32 runs to the fixed contact of microswitch 82, while a conductor I33 runs from the movable contact of microswitch 82 to conductor I3I. When the movable contact I25 of switch E'engages contact I2I at a medial position between the contacts I26 and I28, of course the switch E is open.

Another conductor I34 runs from the third contact of the motor GI to one side of a condenser I35. From the other side of the condenser I35, a conductor I36 runs to the second movable contact I31 of the double-pole three-position switch E. The movable contact I31 may be selectively engaged with any one of three contacts I40, MI, and I42. A conductor I43 runs from contact I40 to connect with conductor III and thus with conductor I23 back to the motor BI. A conductor I44 runs from contact I42 to connect with conductor I24 which returns to the motor 6 I. The contact MI is located'medially between the two contacts I40 and I42, and of course when the movable contact I3I engages with contact I4I, the switch E is open. The two movable contacts I25 and I3? are ganged mechanically so as to be moved together.

Considering now merely the circuits to the motor 6| and assuming that the two microswitches 8 I and 82 are closed and that the doublepole three-position switch E is swung to the position shown on Fig. 12, circuits will be established when the line switch I I0 is closed to cause the motor to turn in a single direction, for example, a clockwise direction. Thus one circuit will be established to the motor GI through plug I2I, conductor I22, line switch I I0, conductor I I I,

, conductor I23, to the motor and thence from the motor through conductor I24, movable contact I25, fixed contact I26, conductor I29, through microswitch 8|, conductor I30, conductor I3I, and conductor II2 to the line plug I2I. A condenser circuit will be established from the motor GI through conductor I34, condenser I35, conductor I36, movable contact I31, fixed contact I40, conductor I43, conductor III, and conductor I23 back to the motor. After the motor 6I has been operated in one direction to rotate the turntable shaft Ill to such a position that the actuating arm II is brought into engagement with the button 8 I a of microswitch 3 I this switch 8| will open, thereby opening the motor circuit even though the line switch H0 remains closed and thereby stopping the motor 5 I. To again actuate the motor it will then be necessary to throw the doublepole three-position switch E to such a position that the movable contact I25 engages the fixed contact I28, and the movable contact I31 engages the fixed contact I42. Thereupo-n a motor circuit will be established from one contact of the line plug I2I through conductor I22, line switch H0, and conductor I23 to the motor and thence from the motor through conductor I24, movable contact I25, fixed contact I23, conductor I32, to the microswitch 82, which is of course closed, thence through conductor I33, conductor I3I, and conductor I I2, back to the other contact of the line plug I2 I. A condenser circuit will be established from the motor BI through conductor I34, condenser I35, conductor I36, movable contact I31, fixed contact I42, conductor I44, and conductor I24 back to the motor GI. These two circuits to the motor will cause the motor to rotate in an opposite direction than formerly, for example, a counterclockwise direction, causing the turntable shaft 5| to rotate in an opposite direction and moving the operating arm TI to a position where it will eventually engage the button 82a. of the microswitch '82,, thereby opening the .microswitch .8'2 and stopping the motor 6 I. Each time that the switch E is thrown to a new closed position, therefore, the motor will be operated in a direction reverse from that in which it has been previously operated until one of the two microswitches BI or '82' is opened to shut oil" the motor. In some instances it may be desirable to stop the motor BI at a given position, and this can be readily done without opening the line switch HD by moving the switch E to a neutral position, i. e., to a position where the two movable contacts I25 and I31 respectively engage the fixed contacts I21 and MI.

A conductor H8 taps the secondary winding of the transformer H3 and runs from the secondary winding to connect with the brush H3, which is in contact with the collector ring H5. From the collector ring a conductor H1 runs to a resistance I45, and a conductor I46 runs from this resistance to the light bulb 33, from whence the circuit is grounded through a conductor I41, the ground being actually efiected through the frame of the machine. Accordingly a light circuit is established when the transformer H9 is energized, from the secondary winding of the transformer through conductor H8, brush H3, slip-ring H5, conductor H1, resistance I45, conductor I45, to the light bulb 33, and thence through conductor I41 to ground.

From the secondary winding of the transformer H9 a conductor I48 runs to the rectifier I29, an other conductor I49 running from the rectifier to one of the contacts as the fixed contact of the hand switch I 09. From the hand switch I89 a conductor I55 runs to one of the two fixed contacts II of the double-pole double-throw relay switch F. This switch includes another fixed contact I 52 in opposition to the fixed contact I 5 i, and between these two fixed contacts are located two movable contacts I53 and I54 respectively, which are operated by the armature for the relay I 55 of the switch F, the two movable contacts 553 being ganged together mechanically. The movable contact 553 of switch F connects with a conductor I55 running to the recording head relay 99, and a conductor 351 runs from this relay 99 back to the other end of the secondary winding of the transformer and to a ground I58. Condensers I59 are interposed between the two conduct-ors I49 and I51.

As has been before explained, the armature I85 of the recording head relay 99 carries a movable contact I94, which is adapted for cooperative engagement with a fixed contact I55. From the fixed contact I52 of switch F, a conductor I55 runs to the fixed contact I55, and a conductor runs from the movable contact I04 to the conductor I From the conductor I53 another conductor I 55 runs to the relay I55 of the switch F, while another conductor 552 runs from the relay 555 to connect with the conductor I55.

Assuming that the line switch I I9 is closed and that the primary circuit to the transformer HS has therefore been established, of course the light will be established to energize the light bulb 33. Then as the hand, switch I59 is closed, a recti ed recording head relay circuit will be temestahlished from the secondary winding of transformer H9, conductor I48, rectifier I25, conductor 49, hand switch I29, conductor I58, fixed contact iEI, movable contact conductor t the relay 99, and from the relay through conductor back to the other end of the secondary winding of the transformer. As this relay circuit is established, the armature I05 will of course be attracted, thereby actuating the printing key 94 and carrying the movable contact I54 into engagement with the fixed contact I95. As this occurs, assuming the hand switch I09 remains closed, a conditioning circuit will be temporarily established from the secondary winding of transformer H9 through conductor I48, rectifier i212, conductor I49, hand switch I55, conductor I55, conductor IfiI, relay I55, conductor I62, conductor I55, fixed contact I 05, movable contact conductor i53, and conductor I51, back to the other end of the secondary winding of the transformer I23, and accordingly the relay I55 will be energized to cause its armature to be atracted and thereby swing the two movable contacts I53 and I54 to bring the movable contact I53 out of engagement with the fixed contact I51 and to carry the movable contact I54 into engagement with the fixed contact As the conditioning circuit is established, the recording relay circuit is broken by the movement of the movable contact I53 away from the fixed contact I5I and accordingly the relay 99 will be deenergized, whereupon the relay armature I09 will no longer be attracted and the movable contact I54 of the switch D will move out of engagement with the fixed contact I55 to break the conditioning circuit. Beiore the conditioning circuit is broken, however, what may be called a hold circuit will be established through the relay I55 of switch F to prevent a second energization of the recording head relay 99 and a consequent second actuation of the printing key 94 as long as the hand switch I09 remains closed and in fact until the hand switch IE9 is first opened and then closed a second time. This hold circuit will be established from the secondary winding of the transformer H9 through conductor I48, rectifier i252, conductor I 49, hand switch I59, conductor I50, conductor I6I, relay I55, conductor I52, fixed contact I52, movable contact I54, and a conductor HSI running from the movable contact I54 to the conductor I51, and thence through the conductor I51 back to the other end of the secondary winding of the transformer I I9. This hold circuit will remain closed to keep the relay I55 of switch F energized until it is broken by the opening .of the hand switch I09.

Referring now to Fig. 11, there is there illustrated a typical chart which may be employed for use with the machine in recording the field of vision of one eye of a patient. This chart will carry certain printed indicia I62 thereon, such as the words Top, Eye, Color, Date, and Name, the word Top indicating that the edge of the chart near where the word is printed is the top or upper part of the chart. Adjacent the word Eye is a blank space which can be filled in with the word left or right to indicate which eye of the patient is being charted. A blank space will be left near the word color to indicate the color of the colored filter plate 45 used in making the plot, and of course the date and name of the patient will be filled in adjacent the words Date and Name on the chart. The chart is divided by vertical and horizontal coordinate lines I63 and I64, which intersect at the center of the chart, and the chart will also preferably have printed thereon concentrically disposed lines I65 with appropriate degree numerals adjacent each to indicate the visual angle to these lines from a straight forward line of sight of the patient. Other radial lines I 66 may also be printed on the chart for ready reference in dividi i ing the chart through the rotational degrees of a circle.

Preparatory to determining and plotting the field of vision of one eye of the patient, one of the printed charts B, which will represent the possible field of vision of a normal human eye, will be placed on the turntable 53 and secured thereon by catching the corners of the chart in the four corner receivers 54 of the turntable. The main line switch I IE] will then be closed, and we can assume that at that time the operating arm 11 is in engagement with the push key 82a of the microswitch 82 and that the light housing is slid to its closest position toward the axis of the shaft 26 and that the recording head C is in its closest position toward the axis of the turntable shaft BI. Let us assume that it is the left eye of the patient to be first examined. The head of the patient will be positioned on the chin rest 23 substantially as shown in Fig. 3, proper adjustment of the standard 22 having been made in the clamping socket ZI to bring the left eye of the patient in alignment with the target 49. The patient will be asked to look fixedly ahead with the line of sight from the left eye directed straight forwardly to the target 49 as indicated by the dotted line IB'I indicated on Fig. 3. The double-pole three-position control switch E will now be actuated to draw it to the position shown in Fig. 12, whereupon the motor BI will be set in shaft 26 rotates, the carriage 36 will be moved by the spiral track 4| outwardly on the guide rods 29 and the light bulb 33, which is of course now lit, will successively throw a beam of light intermittently through the successive apertures in the backing plate 40 being directed through these apertures by the tube 34. The beam of light will first pass through the colored filter plate 45, where it may be given a desired characteristic color and will then pass through the apertures 41 in the plate 46 to strike the diffusion plate 48 of the screen, and successive dots of light will thus appear intermittently on the screen A, which is disposed normal to the straight forward line of vision I6! of the eye of the patient. The patient will of course carry the hand switch I09 in his hand, and each time that he observes a dot of light on the screen A he will press the key Ill9a of the switch I09, temporarily closing this switch.

Of course as the carriage 313 works outwardly relative to the spiral track 4I under rotation of the shaft 26, similarly the recording head C moves outwardly along a radial line relative to the turntable 53 and chart B carried thereon, movement being accomplished by reason of the pin 60 being guided by the spiral track 55. As the patient observes one of the dots of light on the screen A and immediately thereafter presses the key I09a of the hand switch I09, the recording head C will be in a position over the chart B which corresponds relative to the coordinates I63 and I64 of the chart to the position that the light dot appears on the screen A. As the hand switch I Q9 is closed, the recorder C will be actuated rapidly a single time irrespective of the length of time that the patient holds his finger on the key I 09a, and the key 94 will carry a portion of the inked ribbon against the chart and print a spot on the chart which corresponds to the position that the dot of light appears on the screen A as viewed by the eye of the patient. Thus each time that,

a dot of light appears on the screen a corresponding dot will be printed at the proper position on the chart B, and of course if the patient does not observe with his eye a light dot on the screen A at any particular point that a light dot is displayed, there will be no record on the chart B that at that particular point a light dot was seen.

Eventually the carriage 30 will have traversed the entire screen A while the recording head C will have traversed the entire chart B. When this entire traverse has been completed, the arm will strike the key 8Ia of the microswitch 81, thereby opening the circuit to the motor, as has been explained, and the parts will then become stationary. At such time the light carriage 3| will be at its extreme outward position relative to the axis of the shaft 26, and the recording head C will be at its extreme outward position relative to the axis of the turntable shaft 5 I.

If now it is desired to test the right eye of the patient, the first chart B will be removed and it will be replaced with a fresh chart B, whereupon the chin rest 23 can be rotated through and the chin of the patient can be again supported on the chin rest and the right eye directed to the target 49. Thereupon the switch E will be thrown to carry the two movable contacts I25 and I31 into engagement with fixed contacts I40 and I42 respectively, and the motor 6I wil1 then rotate in the opposite direction than formerly and a recording can be made on the new chart B of the field of vision of :the right eye of the patient. During this second recording, the light carriage 30 will be moved inwardly toward the axis of the shaft 25, while the recording head C will be moved centrally toward the axis of the turntable shaft 5I.

When recordings of the two eyes have been completed, the dots on the two charts B, one for the left eye and one for the right eye, will accurately show the points where the patient has observed the light dots on the screen, and thus a complete graph of the field of vision of each eye will be produced. If either eye is abnormal, there may be blank spaces in the chart for that particular eye which will indicate that the eye is blind in certain portions of the field of vision of a normal eye. From this fact the doctor examining the charts may gain useful information which will be of assistance in treating the patient.

In charting the field of vision of an eye, it may be desirable to stop the movement of the light carriage 30 and of the recording head C at certain points where a light dot is exposed to view on the screen A in order to explore meticulously a certain portion of what should be a normal field of vision. The machine may be stopped at any point by throwing the switch E. to the neutral position where the two movable contacts 525 and I3? engage with the fixed contacts I21 and MI respectively, whereupon by operating the switch E to either one of the other two positions, the device can be moved in whichever direction is desired to explore the field of vision in greater detail.

It will be seen that a highly effective method and device have been provided for determining and recording the field of vision of the human eye. It will also be seen that the machine can be used to rapidly explore the field of vision of the eye.

It will of course be understood that various changes may be made in the steps in the process and that various changes may be made in the form, details, arrangement, and proportions of the parts of the apparatus without departure from the scope of the present invention, which, generally stated, consists in the matter shown and described and set forth in the appended claims.

I claim:

1. A device for plotting the field of vision of the eye of a patient comprising ascreen,a light source behind the screen, means for movin said light source through a spiral path emanating from the center of the screen, means for exposing the light source to view through said screen at fixed points in the path of travel of the light source and obscuring the light source from view at other points in its path of travel, a turntable rotating in timed sequence with rotation of said light source, a chart representing the possible field of vision of the eye of the patient and adapted to be mounted on said turntable, a recording head for marking said chart overlying said turntable, means under the control of the patient for actuating said recording head to record an impression on said chart each time that the light source is viewed, means for moving said recording head over said turntable radially inwardly and outwardly of the turntable as the light source is moved radially inwardly and outwardly relative to the center of said screen at a distance which bears the same ratio to the size of the chart that the radial spacing of the light source from the center of the screen bears to the size of the screen.

2. The structure defined in claim 1, said recording head actuating means including a switch adapted to be closed by the patient, and means preventing other than a single instantaneous actuation of the recording head as said switch is closed until after the switch has been opened.

3. A device for plotting the field of Vision of the eye of a patient comprising a screen, a spiral track applied to the rear portion of the screen, a revolving head, a light carriage mounted for slidin radial movement on said head relative to the axis of rotation of the head, a, light mounted in said carriage, means guiding said carriage in said spiral track, a light tube for transmitting a beam from said light to the rear of said screen, said screen having numerous perforations therein into alignment with which said tube is adapted to be successively carried, a turntable, a chart adapted to be carried by the turntab1e,'a recording head overlying said turntable, a spiral track carried by said turntable, means cooperating with said last mentioned spiral track for guiding said recording head radially inwardly and outwardly relative to said turntable proportionately to the chart carried thereby as the light moves radially inwardly and outwardly relative to the axis of rotation of said head, means for rotating said turntable and said head at the same speed, and means under the control of the patient for actuating said recording head to print an impression on said chart.

4. The structure defined in claim 3, a target centrally mounted on said. screen, and means for supporting the head of the patient with the eye to be tested directly forward of said target.

5. A device for plotting the field of vision of the eye of a patient comprising a casing, a screen mounted in the forward portion thereof, a rotary head behind the screen, a light carriage radially slidable on said head, a spiral track at the rear of said screen, a light mounted in said carriage, a light tube aligned with said light guided by said spiral track and directed forwardly from said light, said screen having numerous perforations therein arranged in a spiral path into alignment with which said tube is adapted to be successively brought, a turntable mounted for rotation in said casing, means for driving said turntable and rotary head at the same speed, a recording head guided for radial movement over said turntable, guide pins carried by said recording head and working within said last mentioned spiral track, and means under the control of the patient for actuating said recording head to print an impression on a chart carried by said turntable.

HOWARD D, SHEKELS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,201,631 Rowntree Oct. 17, 1916 1,275,234 Elsom Aug. 13, 1918 1,296,305 Mehren Mar. 4, 1919 1,780,291 Cameron Nov. 4, 1930 1,959,217 Pieper May 13, 1934 2,374,854 Feinbloom May 1, 1945 2,441,031 Papritz May 4, 1948 FOREIGN PATENTS Number Country Date 211,638 Germany July 8, 1909 OTHER REFERENCES Poser (publication) The Perimeter from the Optical Journal and Review of OptometryJanuary 1, 1945pages 23, 24 and 38.

Patrick (publication) The Projection Scotometer from The OpticianJune 4, 1948pages 489 and 490. 

